He has now signed a contract that he says guarantees the Coalition will not break any of its election pledges.

"I"m happy to resign if I don't deliver on these promises," Mr O'Farrell said.

"The people of New South Wales deserve a break, the people of New South Wales need real change."

The Coalition's election commitments include lowering taxes and building the south-west and north-west rail links.

"This is a stunt Mr O'Farrell borrowed from Newt Gingrich in 1994, from David Cameron in the recent UK election," said Ms Keneally, who today promised to spend $5 million over the next four years on early intervention programs for Aboriginal children.

"Just check if this contract has a cooling off period," she said.

"David Cameron took 10 days before he ripped it up."

While Greens MP David Shoebridge says pre-election contracts "aren't worth the paper they're written on", he says they do give voters an insight into a party's priorities.

"The failure to give any guarantee in jobs in New South Wales, the failure to include any environmental commitments to those key issues like our national marine parks shows that Barry O'Farrell's agenda post-election is going to be anti-jobs and anti-environment," he said.

One million copies of Mr O'Farrell's contract will be sent to families across the state.